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Table 3 Factors associated with increasing lytA cycle threshold value (Ct-value) among lytA-positive patients hospitalized with severe acute respiratory illness at Chris Hani-Baragwanath Academic Hospital, Soweto, South Africa, 2009–2012

From: Assessing the impact of pneumococcal conjugate vaccines on invasive pneumococcal disease using polymerase chain reaction-based surveillance: an experience from South Africa

Variable

lytA Ct-value

Proportional-Odds Model

Univariate analysis

Multivariable analysis

Total

n (%)

≤30

n (%)

31-34

n (%)

≥35

n (%)

ORb

(95 % CI)

p-value

aORb

(95 % CI)

p-value

Age (in years)

N = 603

N = 71

N = 128

N = 404

    

 <2

125 (20.7)

6 (8.5)

11 (8.6)

108 (26.7)

Reference

-

  

 2–4

24 (4.0)

0 (0.0)

6 (4.7)

18 (4.5)

0.5 (0.2-1.5)

0.227

  

 5–24

44 (7.3)

2 (2.8)

13 (10.2)

29 (7.2)

0.3 (0.2-0.7)

0.008

  

 25–44

268 (44.4)

48 (67.6)

59 (46.1)

161 (39.8)

0.2 (0.1-0.4)

<0.001

  

 45–64

135 (22.4)

14 (19.7)

37 (28.9)

84 (20.8)

0.3 (0.1-0.5)

<0.001

  

 ≥65

7 (1.2)

1 (1.4)

2 (1.5)

4 (1.0)

0.2 (0.1-1.1)

<0.051

  

Sex

N = 603

N = 71

N = 128

N = 404

    

 Male

257 (42.6)

27 (38.0)

64 (50.0)

166 (41.1)

Reference

-

  

 Female

346 (57.4)

44 (62.0)

64 (50.0)

238 (58.9)

1.1

0.453

  

Year

N = 607

N = 71

N = 129

N = 407

    

 2009

129 (21.3)

8 (11.3)

18 (13.9)

103 (25.3)

Reference

-

  

 2010

173 (28.5)

34 (47.9)

46 (35.7)

93 (22.8)

0.3 (0.2–0.5)

<0.001

  

 2011

150 (24.7)

10 (14.1)

39 (30.2)

101 (24.8)

0.6 (0.3–0.9)

0.033

  

 2012

155 (25.5

19 (26.8)

26 (20.2)

110 (27.0)

0.6 (0.3–1.1)

0.064

  

Extraction Instrument

N = 607

N = 71

N = 129

N = 407

    

 Roche MagNA Pure LC 1.0

136 (22.4)

9 (12.7)

19 (14.7)

108 (26.5)

Reference

-

Reference

-

 Roche MagNA Pure LC 2.0

400 (65.9)

54 (76.1)

96 (74.4)

250 (61.4)

0.4 (0.3–0.7)

<0.001

0.4 (0.2–0.6)

<0.001

 Roche MagNA Pure 96

71 (11.7)

8 (11.3)

14 (10.8)

49 (12.0)

0.6 (0.3–1.1)

0.092

0.3 (0.1–0.7)

0.004

Antibiotics 24H before admission

N = 601

N = 71

N = 128

N = 402

    

 No

567 (94.3)

68 (95.8)

122 (95.3)

377 (93.8)

Reference

-

  

 Yes

34 (5.7)

3 (4.2)

6 (4.7)

25 (6.2)

1.4 (0.6–3.0)

0.393

  

Antibiotics during admission

N = 586

N = 69

N = 126

N = 391

    

 No

19 (3.2)

3 (4.3)

2 (1.6)

14 (3.6)

Reference

-

  

 Yes

567 (96.8)

66 (95.6)

124 (98.4)

377 (96.4)

0.8 (0.3–2.2)

0.647

  

Underlying medical conditionsa

N = 603

N = 71

N = 128

N = 404

    

 No

565 (93.7)

66 (93.0)

120 (93.7)

379 (93.8)

Reference

-

  

 Yes

38 (6.3)

5 (7.0)

8 (6.3)

25 (6.2)

0.9 (0.5–1.8)

0.839

  

HIV infection

N = 558

N = 66

N = 119

N = 373

    

 No

163 (29.2)

5 (7.6)

22 (18.5)

136 (36.5)

Reference

-

Reference

-

 Yes

395 (70.8)

61 (92.4)

97 (81.5)

237 (63.5)

0.3 (0.2–0.5)

<0.001

0.4 (0.2–0.7)

0.001

PCV serotypes/serogroups

N = 607

N = 71

N = 129

N = 407

    

 PCV-7

111 (18.3)

13 (18.3)

28 (21.7)

70 (17.2)

Reference

-

Reference

-

 PCV-13

138 (22.7)

35 (49.3)

62 (48.1)

41 (10.1)

0.3 (0.2–0.5)

<0.001

0.3 (0.2–0.5)

<0.001

 NVT

358 (59.0)

23 (32.4)

39 (30.2)

296 (72.7)

2.7 (1.7–4.4)

<0.001

2.7 (1.6–4.6)

<0.001

Duration of symptoms (in days)

N = 602

N = 71

N = 127

N = 404

    

 0–2

204 (33.9)

14 (19.7)

38 (29.9)

152 (37.6)

Reference

-

  

 ≥3

398 (66.1)

57 (80.3)

89 (70.1)

252 (62.4)

0.6 (0.4–0.8)

0.003

  

Duration of hospitalization (in days)

N = 602

N = 71

N = 129

N = 402

    

 0–2

92 (15.3)

1 (1.4)

15 (11.6)

76 918.9)

Reference

-

Reference

-

 3–7

267 (44.3)

26 (36.6)

61 (47.3)

180 (44.8)

0.4 (0.2–0.8)

0.004

0.5 (0.2–1.1)

0.071

 ≥8

243 (40.4)

44 (62.0)

53 (41.1)

146 (36.3)

0.3 (0.1–0.5)

<0.001

0.3 (0.1–0.6)

0.002

In-hospital outcome

N = 603

N = 71

N = 129

N = 403

    

 Survived

562 (93.2)

58 (81.7)

119 (92.2)

385 (95.5)

Reference

-

Reference

-

 Died

41 (6.8)

13 (18.31)

10 (7.8)

18 (4.5)

0.3 (0.2–0.6)

<0.001

0.3 (0.2–0.7)

0.003

  1. Abbreviations: OR: odds ratio; aOR: adjusted odds ratio; CI: confidence interval; HIV: human immunideficency virus; PCV-7: 7-valent pneumococcal conjugate vaccine serotypes (included serotypes/serogroups 4, 6A/B, 9A/V/L/N, 14, 18A/B/C, 19B/F, 23 F); PCV-13: additional 13-valent pneumococcal conjugate vaccineserotypes (included serotypes/serogroups 1, 3, 5, 7A/F, 19A); NVT: serotypes/serogroups not included in PCV-7 or PCV-13, including samples that tested negative for the 42 serotypes detected by the serotyping assay
  2. a Underlying medical conditions included: asthma, chronic lung disease, chronic heart disease, liver disease, renal disease, diabetes mellitus, immunocompromizing conditions excluding HIV infection or neurological disease
  3. b The odds ratio of the proportional-odds model measures the effect of a predictor on the odds of being above a specified level, compared with the odds of being at or below the specified level
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BMC Infectious Diseases

ISSN: 1471-2334

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